Microsoft Wants an Ad Exchange Too

Not to be left out of the ad exchange party, Microsoft plans to acquire AdECN, an online ad exchange similar to Right Media (acquired by Yahoo) and DoubleClick's (soon to be acquired by Google).

The idea of an ad exchange is similar to a stock exchange, where buyers and sellers work through a broker. Similarly, AdECN does not do business directly with advertisers or publishers; it works instead with ad networks, ad brokers, and a few ad agencies that maintain relationships with buyers and sellers, acting as a network themselves.

If you're keeping score, that leaves newcomer ContextWeb and its ADSDAQ exchange as the last independent player standing in the ad exchange space.